Apparatus for bending metal

ABSTRACT

Metal bending apparatus is provided for progressively bending metal products such as sheets, strips, flat bars, and the like, to a predetermined angle by simple hand pressure, by pivotally moving a bending lever or arm into a wedge-shaped upper surface of a supporting bed. The pivotal mounting of the forward end of the bending arm is made resilient so that the pivoting portion of the bending arm automatically elevates in response to the thickness of the material being bent to minimize the variation which occurs in the angle of the bend along the length thereof.

United States Patent Inventor Bruno Speiser Syosset, N.Y. App]. No.828,595 Filed May 28, 1969 Patented June 8, 1971 Assignee Josephson,Speiser & has

New York, N.Y.

APPARATUS FOR BENDING METAL 6 Claims, 3 Drawing Figs.

US. Cl 72/387, 72/346, 72/465 lnt.Cl BZld 5/01 Field of Search 72/446,

[56] References Cited UNITED STATES PATENTS 437,829 10/1890 Born 72/3192,754,878 7/1953 Yoho 72/319 Primary ExaminerRichard J. Herbst AssistantExaminerGene P. Crosby An0rneyArnold G, Gulko ABSTRACT: Metal bendingapparatus is provided for progressively bending metal products such assheets, strips, flat bars, and the like, to a predetermined angle bysimple hand pressure, by pivotally moving a bending lever or arm into awedge-shaped upper surface of a supporting bed, The pivotal mounting ofthe forward end of the bending arm is made resilient so that thepivoting portion of the bending arm automatically elevates in responseto the thickness of the material being bent to minimize the variationwhich occurs in the angle of the bend along the length thereof.

PATENTED JUN 22 197i YINVENTOR 6y BRUNO SPE/SER A T TORNE Y APPARATUSFOR BENDING METAL The present invention relates to improvements inapparatus for bending metal of thetype in which a progressive bendingpressure is applied by pivotally moving a bending lever or arm into awedge-shaped upper surface ofa supporting bed. In the prior structuresof this type, the pivotal bending arm was provided with a fixed pivotwhich was poorly adapted for the bending of metal products of varioustype including sheets, strips, flat bars, and the like, because the bendmade near the pivot is sharper and more angular than the bend remotefrom the pivot. Thus, the angle ofthe bend varies significantly alongthe length of the bend, and the longer the length ofthe bend, thegreater the undesired variation.

The principal purpose of this invention is to vary the structure of thebending apparatus in order to minimize the variation which occurs in theangle of the bend along the length thereof so that metal products can bemore efficiently and accurately bent without employing cumbersome andexpensive equipment such as the brakes normally employed for thepurpose.

The present invention is therefore directed to improvements in a knowntype of metal bending apparatus in which a bed has a wedge-shaped uppersurface and a bending arm has its forward end pivotally secured to theforward end of the bed so that the bending arm enters the wedge portionof the bed from front to rear as the bending arm is pivoted. This knownapparatus is useful for the bending ofmetal products including sheets,strips, flat bars, rods, and similar materials. The improvement in theinvention relates to the pivotal mounting of the forward end of thebending arm whereby the pivoting portion of the bending armautomatically elevates as needed in response to the thickness of theproduct being worked upon. In this way, the bend imposed upon theproduct will be relatively constant along the length thereof.

The invention will be more fully understood from the accompanyingdrawings in which:

FIG. 1 is a perspective view of the bending apparatus of the invention;

FIG. 2 is a cross section taken through the middle of the apparatus withthe bending arm in bending position and looking toward the forward endof the apparatus; and

FIG. 3 is a cross section taken on the line 3-3 of FIG. 2.

Referring to FIG. I, the bending apparatus includes a bed 10, a bendingarm 11 and pivot means 12 which generically identifies the pivotalinterconnection between the forward end of the bending arm 11 and theforward end the bed 10.

The bed is a single casting having sidewardly extending cars 13 whichare bored at 14. It is advisable to secure the bed to a work support andthis may be done using "C" clamps or, preferably, by bolts which arepassed through the holes 14. The bed 10 may also include a groove G tofacilitate the bending of rods and tubes.

The upper surface of the bed 10 constitutes a female die and iswedge-shaped as shown at 17. The upper corners of the wedge, identifiedat 15 and 16 are preferably rounded and smoothed so as not to mar thesheet being bent since this sheet slides over the upper corners l5 and16 as the bent portion thereof is forced downwardly into the wedgeportion of the bed.

The bending arm 11 has a raised handle portion 18 and a knife portion 19which moves into the wedge portion 17 as the bending arm 11 is pivotedby lowering the handle 18.

The forward end of the bed 10 is formed with upstanding portions 21 and22 which are formed integrally with the for ward end of the bed. Theforward end of the bending arm 11 is formed to fit within the upstandingportions 2! and 22 and this serves to align the knife portion I9 of thebending arm 11 with the axis of the wedge portion 17.

A pivot pin 23 is inserted through the upstanding portion 21, thenthrough the forward end of the bending arm 11 and lastly through theupstanding portion 22 so as to pivotally mount the bending arm 11 andthe forward end of the bending arm 11 which fits between the upstandingportions 21 and 22 includes a compensating aperture extending laterallytherethrough in order to accommodate the pin 23. This aperture is animportant feature of the present construction and can be seen in dottedlines in FIG. 2 of the drawing where it is identified by the numeral 24.The aperture 24 is approximately the same size as the pin 23 along thelength of the bending arm 11 to minimize movement of the arm 11 alongits own length, but the aperture 24 is oversized in the direction of theheight of the knife portion I9 so that the forward end of the arm 11 canbe elevated by the back pressure generated through bending contactbetween the knife portion 19 and the sheet or bar being bent. Thiselevation occurs after the metal being bent is forced to the bottom ofthe wedge portion 17 and serves to align the bending edge of the knifeI9 with the upper surface of the sheet being bentwhich will vary withthe thickness of the sheet being bent.

Referring again to FIG. 2, the pivot pin 23 is constituted by a boltwhich extends laterally through the entire structure which is heldtogether by the bolt head at one side and, at the other side, by meansof a nut 25 threaded on the free threaded end of the bolt. A yoke 26extends across the upstanding portions 21 and 22 with its opposite ends27 and 28 being pivoted to the opposite ends of'the pin 23. Washers 29and 30 are desirably interposed between the upstanding portions 21 and22 and the head of the pin 23 on one side and the nut 25 on the otherside to permit the yoke 26 to swing with the bending arm 11 as said armis pivoted. While any form of shaft may be used to form the pivot pin, abolt and nut as described are particularly convenient.

A retaining bolt 31 extends through the upper portion of the yoke 26 andis threaded into a tapped hole 32 in the forward end of the bending arm11 immediately above the compensating aperture 24. The bolt 31 ties theyoke 26 to the pivoted end of the arm 11 so that the two will swingtogether. Lastly, a compression spring 33 is mounted on the retainingbolt 31 to bear downwardly against the forward pivoted end of thebending arm 11 to force the same as far down as possible. It is thespring 33 which resiliently resists the upward movement of the pivotedend of the bending arm 11 and which enables the pivoted end of arm 31 torise and adjust for the thickness of the product being bent.

The action will be more clearly seen in FIG. 3 in which the bending of asheet is illustrated.

As the knife portion 19 contacts the sheet to be bent at its forward endand moves this sheet to the bottom of the wedge 17, downward pivotalpressure applied to the handle 18 tends to cause the forward end of thebending arm 11 to rise as indicated by arrow A against the pressure ofspring 33. The fulcrum for this pivotal movement is at F. As a result,the effective pivot point provided by pin 23 is automatically shifted toposition the bending edge of the knife portion 19 at the level of theupper surface of the sheet to be bent. This enables full entry of theknife 19 into the wedge 17 along its entire length and, thus, the angleof bend at the rear of the sheet is substantially the same as the angleof bend at the forward end of the sheet to provide the uniform bendangle desired.

When contact is initially made with the sheet being bent, the leverageis great and is effective to overcome the pressure of spring 33. On theother hand, the leverage decreases as the knife 19 contacts the metalsheet to be bent further and further away from the pin 23. Moreover,when the rear of the sheet being bent reaches the bottom of wedgeportion 17, the bend is complete and further heavy pressure has nopurpose. As a result, after the compensating action has taken place,further elevation of the forward end of the bending arm 11 does not takeplace.

While the novel feature of the invention is particularly adapted tofacilitate the bending of sheets, with the advantage of the inventionincreasing with bends of increasing length, the apparatus of theinvention is nonetheless useful for bending flat bars and rods, thoughthe automatic compensating feature is less significant in such otherutilities. Similarly, while metal products are particularlycontemplated, plastic and other materials can also be worked upon.

It will now be apparent that the present development is founded onemploying a resilient pivotal interconnection between the forward end ofthe bending arm 11 and the forward end of the supporting bed with meansto bias the forward end of the bending arm downwardly toward the bed.This resilient pivotal interconnection is preferably provided byemploying a vertical elongated aperture in the forward end of thebending arm to receive the pivot pin with the downward resilient biasbeing preferably provided by means of a yoke carried by said pivot pinand which extends across the top of the forward end of the bending arm.A compression spring is interposed between the top of the yoke and theforward end of the bending arm overlying the pivot and with the yoke andbending arm being locked together so that the two will swing togetherand maintain the compression spring at a right angle to the length ofthe bending arm.

It is also desirable to be able to accurately position an edge of themetal sheet to be bent at a predetermined distance from the line of bendand this is achieved in the invention utilizing a measuring ledge 34which extends sidewardly from the upper surface of the bed 10. As willbe evident, a sheet is rested flat on the bed with its edgeappropriately positioned on the measuring ledge 34. When the bending arm11 descends into the wedge 17, the portions of the metal being bent onopposite sides of the line of bend shift upwardly until, when the knifeportion 19 has descended fully into wedge 17, the metal willsubstantially conform to the shape of the wedge which usually is formedto a 90 angle, but which may be formed to other angles if desired.

The invention is defined in the claims which follow.

I claim: 1. ln apparatus for bending metal comprising a bed having awedge-shaped upper surface and a bending arm having its forward endpivotally secured to the forward portion of the bed above said wedge sothat the bending arm enters said wedge progressively from front to rearas the bending arm is pivoted to lower said arm, the improvementcomprising a resilient pivotal interconnection between the forward endof said bending arm and the forward end of said bed and means biasingthe forward end of said bending arm downwardly toward said bed.

2. The improvement recited in claim 1 in which said resilient pivotalinterconnection includes a compensating aperture in the forward end ofsaid bending arm and a pivot pin carried by the forward end of said bedand extending through said aperture, said aperture being verticallyelongated to permit the forward end of the bending arm to rise withrespect to said pivot pin.

5. The improvement recited in claim 4 in which said yoke is locked tosaid bending arm by means of a threaded retaining bolt which extendsthrough the top of the yoke into a tapped hole in the forward end ofsaid bending arm.

6. The improvement recited in claim 1 in which said bed includes ameasuring ledge which extends sidewardly from the upper surface of saidbed.

1. In apparatus for bending metal comprising a bed having a wedge-shapedupper surface and a bending arm having its forward end pivotally securedto the forward portion of the bed above said wedge so that the bendingarm enters said wedge progressively from front to rear as the bendingarm is pivoted to lower said arm, the improvement comprising a resilientpivotal interconnection between the forward end of said bending arm andthe forward end of said bed and means biasing the forward end of saidbending arm downwardly toward said bed.
 2. The improvement recited inclaim 1 in which said resilient pivotal interconnection includes acompensating aperture in the forward end of said bending arm and a pivotpin carried by the forward end of said bed and extending through saidaperture, said aperture being verTically elongated to permit the forwardend of the bending arm to rise with respect to said pivot pin.
 3. Theimprovement recited in claim 2 in which a yoke carried by said pivot pinextends across the top of the forward end of said bending arm and acompensating spring is interposed between the top of said yoke and theforward end of the bending arm overlying said pivot pin.
 4. Theimprovement recited in claim 3 in which said yoke and said bending armare locked together so that the two will swing in unison to maintainsaid compensating spring at a right angle to the length of the bendingarm.
 5. The improvement recited in claim 4 in which said yoke is lockedto said bending arm by means of a threaded retaining bolt which extendsthrough the top of the yoke into a tapped hole in the forward end ofsaid bending arm.
 6. The improvement recited in claim 1 in which saidbed includes a measuring ledge which extends sidewardly from the uppersurface of said bed.